The present invention relates to an alarm system for the copying machine for giving the audio or visual warning signal to an operator if he or she leaves the copying machine without taking a master after the completion of copying operation.
In general, various persons use one copying machine and it occurs very frequently that, after obtaining a desired number of copies, one gives attention only to taking out the copies from the discharge tray and forgets to take out his or her master from the master stand. If the copying machine is used so very frequently that the next user is waiting, he or she immediately notices the master left behind and can give the warning to the former user who left behind the master. However, when the master is left over the master stand for a long time, it becomes difficult to trace the owner of the left-behind master and consequently the master is lost.
In order to solve this problem, there has been devised and demonstrated an alarm system of the type in which a master detection switch and a power switch are interlocked in such a way that when the power switch is turned off without taking the master out of the copying machine, an alarm indicator is activated. This system has the distinctive defect that the alarm indicator remains deactivated unless the power switch is turned off. As a result, this system cannot be applied to the dry-type copying machine which is normally kept connected to the power supply.
There has been also proposed a master detection device of the type comprising a light source and a light sensor both of which are disposed under a contact glass of a copying machine and a reflecting mirror mounted on a pressure plate so that the presence or absence of a master on the contact glass is detected by whether the light sensor does not receive or does receive the light reflected back from the reflecting mirror. There has been further proposed a master detection device comprising a switch which is turned on or off when the pressure plate is opened or closed. These master detection devices have been used only for detecting whether a master is set on the contact glass or not and are not used for attaining more useful functions.
There has been further proposed an alarm system of the type which gives the warning signal if a master is not taken out of the contact glass a predetermined time interval after the completion of copying operation. However, it is difficult to set a suitable time interval. That is, if a time interval is too short, the warning signal is generated before the operator takes out the used master and sets the next master on the contact glass. On the other hand, if a time interval is too long, the warning signal is generated only after the operator has already left.